SharpCap Forums

Hi Frank,

Just a heads up of what you can expect from M42. I took this 7.5-minute image (45x10s) with my SeeStar S50. Same as your SpaceCat but you have a better camera. I'm at Bortle 5.3
Brian

That looks great Brian.
I hope to have something late next week.
Frank

Frank,

I see that my SeeStar automatically used the Light Pollution (LP) filter. M42 is a gaseous nebula and does respond well to a narrowband' filter. In advanced setups narrowband filters typically let in only 6 nanometers (nm) of light at a specific wavelength. That's what Dave used with his Hydrogen Alpha (Ha) image of M33. That explains why his exposure was 450 seconds long, but also he has a CCD camera whereas you have CMOS. Yours requires shorter exposures.

The LP filter on the SeeStar passes approximately 40nm combined light of Ha and Double-Ionized Oxygen (OIII). It won't have the crispness of a dedicated mono camera with a single-wavelength narrowband filter, but you'll like the results and cost is reasonable.

I have several filters for my mono camera, but I recently bought an Antlia tri-band filter for the SeeStar.

This link is for a 2-inch filter but you should make sure it fits your filter holder:
https://agenaastro.com/antlia-triband-r ... unted.html

A tri-band filter yields better star color due to the blue band. Dual-band filters only given you the Red and Green at Ha and OIII. The difference is important since you have a color camera. The total bandpass is 80nm compared to 300nm with a conventional IR/UV filter. You will have to expose longer, perhaps 20 seconds instead of 5 seconds.

Brian

Brian
At the moment I have the 2inch UV/IR cut filter I’ve been using. I also have this filter that I have not tried out yet. I intended to use when I got to shooting the Nebulas like Orion. Hope I made a good choice.

SVBONY SV220 Telescope Filter, 2" 7nm Dual-Band Nebula Filter, Reduce Stray Light, H-Alpha&O-III Narrowband Filter

Frank

Frank,

That filter should be fine. I ran it through the calculator. Minimum Exposure is 70 seconds. Looking at the specs, I'm assuming 7nm in Ha + 7nm in OIII, total of 14nm. That should give you a beautiful M42 and M33. Still, having said that avoid the Full Moon to be safe. Ha does well with the Moon but OIII suffers.

Ha + OIII yields stars in the Red to Yellow color range. Not terrible, but not the greatest. In post-production look to see if you can reduce the size of stars; that will help a lot.

Good luck!

Brian

That’s good to hear, thanks.
So with that filter at 70 seconds exposure, same gain of 110, how many frames should I shoot for. I assume the session will take longer at this setting.
The moon will be around 50+/- percent depending on the night(s) I get out there. Hopefully not overhead.
Frank

Frank,

The Moon should be Last Quarter, so plan on it rising approximately 10pm. It'll be far enough away from both objects.

Are you Live Stacking with SharpCap? It should give you the feedback to know when enough is enough integration time. M42 won't take much time, but M33 I'm not certain. The more the better, they say!

Use the same gain.

Brian

Thanks Brian.
Yes Sharpcap.
I’ll keep an eye on it.
Hope to have something nice to show when done.
Frank

Hi Brian
I was looking at your lookup tool last night. Pretty cool and I’ll definitely use it. Couple questions.
1. The green arrows, I am guessing they have something to do with the time range entered?
2. When entering target types, I am finding that if I enter multiples, such as: Galaxies, Nebulae
I get only one type returned. If I enter one type and ASK, I get all that type back.
Please correct me if I am entering these items wrong.
Frank

Brian, never mind on question 1, I jumped on my PC and see the information when hovering.
I was on my phone last night so the hover was not available.
Frank